Effect of acid attack on FRP-to-concrete bonded interfaces

Hadigheh, S. Ali; Gravina, Rebecca; Smith, Scott T

doi:10.1016/j.conbuildmat.2017.06.140

Cited by 67 publications

(35 citation statements)

References 78 publications

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“…The increment in mass loss and compressive strength loss observed when the exposure time increased are consistent with the results obtained in previous studies [26]. The formation of ettringite and gypsum is common in cementitious systems exposed to sulfuric acid solutions and is observed in numerous field and laboratory studies [11,12,44]. Deleterious expansion occurs in mortars due to an excessive amount of these formations.…”

Section: Mass Loss Due To the Sulfuric Acid Exposuresupporting

confidence: 90%

Exposing Sustainable Mortars with Nanosilica, Zinc Stearate, and Ethyl Silicate Coating to Sulfuric Acid Attack

et al. 2018

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Obtaining durable materials that lengthen the service life of constructions and thereby contribute to sustainability requires research into products that improve the durability of cementitious materials under aggressive conditions. This paper studies the effects of sulfuric acid exposure on four mortar types (control mortar, mortar with nanosilica, mortar with zinc stearate, and mortar with an ethyl silicate coating), and evaluates which of them have better performance against the acid attack. After 28 days of curing, the samples were exposed to a sulfuric acid attack by immersing them in a 3% w/w of H2SO4 solution. Physical changes (mass loss, ultrasonic pulse velocity, open porosity, and water absorption), and mechanical changes (compressive strength) were determined after the sulfuric acid exposure. A scanning electron microscope (SEM) was used to characterize the morphology of the surface mortars after the exposure. The control mortar had the highest compressive strength after the acid attack, although of the four types, the zinc stearate mortar showed the lowest percentage of strength loss. The zinc stearate mortar had the lowest mass loss after the acid exposure; moreover, it had the lowest capillary water absorption coefficient (demonstrating its hydrophobic effect) both in a non-aggressive environment and acid attack.

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Section: Mass Loss Due To the Sulfuric Acid Exposuresupporting

confidence: 90%

Exposing Sustainable Mortars with Nanosilica, Zinc Stearate, and Ethyl Silicate Coating to Sulfuric Acid Attack

et al. 2018

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“…An increase in pore refinement of this type of mortar, subjected to attack by the acid, was observed, with a high percentage of finer pores. This is in agreement with the decrease of Hg reduction under the same conditions and can be explained in relation to the silting of the pores by the formation of ettringite and gypsum, whichare produced by a reaction of the pozzolanic products (caused by the sprayed ethyl silicate) with the aggressive ions [4,5]. This process closes the microstructure, reducing its tortuosity, at least until they are filled (when the microcracking phenomenon is predominant).…”

Section: Controlsupporting

confidence: 83%

“…As has been explained, ethyl silicate reacts with the material to which it is applied, producing pozzolanic solid phases [18]. In the initial steps of the sulphuric acid attack, these pozzolanic products react with the aggressive ions, leading to the formation of ettringite and gypsum [4,5] which progressively fill the pores, reducing their sizes. This takes place in part of the microstructure of ethyl silicate samples, as suggested by the pore size distributions obtained (see Figure 2).…”

Section: Mercury Intrusion Porosimetrymentioning

confidence: 99%

“…Acid rain (pH < 5) causes the deterioration of construction material surfaces on which the pollutants are deposited. In addition, several studies show that acid rain generates a layer of gypsum on the substrate [2,3] due to a chemical reaction of sulphuric acid with products of cement hydration (such as calcium silicate hydrate and calcium hydroxide) [4,5], and with calcium carbonate [6] that usually comes from aggregates utilised in the manufacturing of cementitious materials.…”

Section: Introductionmentioning

confidence: 99%

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Pore Structure Degradation of Different Cement Mortars Exposed to Sulphuric Acid

et al. 2019

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Acid attack causes the deterioration of construction material surfaces. The objective of this study was to investigate the degradation of different types of cement mortar in terms of variations in pore size distribution obtained by mercury intrusion porosimetry (MIP), mass loss, and compressive strength. The mortars were manufactured with nanosilica, zinc stearate, and an ethyl silicate coating. After curing (28 days), the samples were subjected to acid exposure for 90 days, immersed ina solution (3% w/w) of sulphuric acid (H2SO4). The results indicate that the mortars showed a more refined microstructure, with a higher proportion of smaller pores (<100 nm) compared to the control mortar. The 28-day and 90-day compressive strength variations of mortars were also determined by observing pronounced reduction due to the appearance of expansive compounds responsible for microcracking.

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“…However, for the specimens subjected to acidic and saline solutions, there were some morphological changes after 30 drying-wetting cycles. In the acidic environment (pH = 1.5), a large number of naked PG particles were observed, which may be related to the dissolution of hydration products [37]. As a result, conjunctions of the PG particles were broken, resulting in spalling of the PG-based backfill from a macroscopic perspective.…”

Section: Microstructurementioning

confidence: 99%

Durability Evaluation of Phosphogypsum-Based Cemented Backfill Through Drying-Wetting Cycles

Zhou

et al. 2019

Minerals

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In this study, the durability of phosphogypsum (PG)-based cemented backfill was investigated by drying-wetting cycles to explore deterioration of its strength and the release of impurities. The leachates in this test were composed of deionized water, 5% Na2SO4 solution, 5% NaCl solution, and a range of sulfuric acid solutions with pH values of 1.5, 3, and 5. After drying-wetting cycles, unconfined compressive strength (UCS), visual deterioration, porosity, microstructure and concentrations of phosphate and fluoride in the leachates were measured. The results showed that both saline and acidic solutions could lead to strength reduction of PG-based cemented backfill under different deterioration mechanisms. The mechanical damage of salinity was caused by micro-cracking and degradation of C–S–H. However, the H+ broke the backfill by dissolving hydration products, leaving the conjunctures between PG particles weakened. Furthermore, the environmental impact was investigated by measuring the concentration of phosphate and fluoride in the leachates. In acidic solutions, the release of phosphate and fluoride was greatly enhanced by H+. Compared to the great strength deterioration in saline leachates, the concentration of phosphate and fluoride were similar to that of deionized water, indicating that saline solutions had little impact on the release of hazardous impurities.

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Effect of acid attack on FRP-to-concrete bonded interfaces

Cited by 67 publications

References 78 publications

Exposing Sustainable Mortars with Nanosilica, Zinc Stearate, and Ethyl Silicate Coating to Sulfuric Acid Attack

Exposing Sustainable Mortars with Nanosilica, Zinc Stearate, and Ethyl Silicate Coating to Sulfuric Acid Attack

Pore Structure Degradation of Different Cement Mortars Exposed to Sulphuric Acid

Durability Evaluation of Phosphogypsum-Based Cemented Backfill Through Drying-Wetting Cycles

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